c# 获取视频采集卡并实时显示到winform中并设置自动大小

以下是使用C#获取视频采集卡并实时显示到Winform中并设置自动大小的示例代码：

using System;
using System.Windows.Forms;
using AForge.Video;
using AForge.Video.DirectShow;

namespace VideoCapture
{
    public partial class Form1 : Form
    {
        private FilterInfoCollection videoDevices;
        private VideoCaptureDevice videoDevice;
        private VideoCapabilities[] videoCapabilities;
        private VideoCapabilities[] snapshotCapabilities;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // 获取可用的视频设备
            videoDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
            foreach (FilterInfo device in videoDevices)
            {
                cbDevices.Items.Add(device.Name);
            }
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            if (cbDevices.SelectedIndex == -1)
            {
                MessageBox.Show("请选择视频设备");
                return;
            }

            if (videoDevice == null)
            {
                // 创建视频采集设备
                videoDevice = new VideoCaptureDevice(videoDevices[cbDevices.SelectedIndex].MonikerString);
                videoDevice.NewFrame += new NewFrameEventHandler(videoDevice_NewFrame);
            }

            // 获取可用的视频分辨率
            videoCapabilities = videoDevice.VideoCapabilities;
            foreach (VideoCapabilities capabilty in videoCapabilities)
            {
                cbResolutions.Items.Add(capabilty.FrameSize.Width + "x" + capabilty.FrameSize.Height);
            }

            // 获取可用的截图分辨率
            snapshotCapabilities = videoDevice.SnapshotCapabilities;
            foreach (VideoCapabilities capabilty in snapshotCapabilities)
            {
                cbSnapshots.Items.Add(capabilty.FrameSize.Width + "x" + capabilty.FrameSize.Height);
            }

            // 开始视频采集
            videoDevice.Start();
        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            if (videoDevice != null)
            {
                // 停止视频采集
                videoDevice.Stop();
                videoDevice = null;
            }
        }

        private void videoDevice_NewFrame(object sender, NewFrameEventArgs eventArgs)
        {
            // 显示视频帧
            pbVideo.Image = (System.Drawing.Image)eventArgs.Frame.Clone();

            // 设置PictureBox自动大小
            pbVideo.SizeMode = PictureBoxSizeMode.AutoSize;
        }

        private void btnSnapshot_Click(object sender, EventArgs e)
        {
            if (cbSnapshots.SelectedIndex == -1)
            {
                MessageBox.Show("请选择截图分辨率");
                return;
            }

            // 设置截图分辨率
            videoDevice.SnapshotResolution = snapshotCapabilities[cbSnapshots.SelectedIndex];

            // 截取当前视频帧
            pbSnapshot.Image = (System.Drawing.Image)pbVideo.Image.Clone();
            pbSnapshot.SizeMode = PictureBoxSizeMode.AutoSize;
        }
    }
}

其中，cbDevices是ComboBox控件，用于选择视频设备；cbResolutions和cbSnapshots也是ComboBox控件，分别用于选择视频分辨率和截图分辨率；pbVideo和pbSnapshot是PictureBox控件，分别用于显示实时视频和截图。

在btnStart_Click事件中，创建视频采集设备并开始视频采集；在videoDevice_NewFrame事件中，将视频帧显示到pbVideo控件中，并设置自动大小；在btnSnapshot_Click事件中，设置截图分辨率并截取当前视频帧，将截图显示到pbSnapshot控件中，并设置自动大小。在btnStop_Click事件中，停止视频采集。

可以根据需要对代码进行修改和优化